select: Competitor Selection Rules

Description

Functions returning TRUE for plants that compete with a given subject plant, or FALSE otherwise. The decision can depend on distance and plant marks. For use in pairwise.

Usage

size.sel(imarks, jmarks, dists, dranks, par = list(k = 0.2, smark = 1))
powlinear.sel(imarks, jmarks, dists, dranks, par = list(ki = 0.2, kj = 0,
  p = 1, r0 = 0, smark=1))

Arguments

imarks

Marks for the subject plant, a 1-row data frame.

jmarks

Data frame with marks for potential competitors

dists

Vector of distances between the subject plant and the potential competitors.

dranks

Distance ranks.

par

List of parameters.

Value

Logical vector of length equal to the length of dists.

encoding

UTF-8

Details

The values of par must be given in the argument selpar of pairwise, they are shown here as examples.

smark in par indicates the location of the plant size variable in marks. It can be a data frame column number, or a string id like "dbh".

size.sel is a simple example where competitors are selected within a radius proportional to plant size. This corresponds to the second example in Section 9.2.1 of Burkhart and Tomé{Tome} (2012).

Note that their first example (fixed radius) is implemented by giving a value to maxR in pairwise, no select function is needed. Similarly, their third example (fixed number of nearest neighbors) is obtained by giving a value to maxN.

powlinear.sel is a general form that covers all the other examples in Burkhart and Tomé{Tome} (2012) with particular values for the parameters (except for the competition elimination angle, which depends on relative positions among competitors): [object Object],[object Object],[object Object],[object Object] These and other examples could be coded directly if computational efficiency is important.

References

http://forestgrowth.unbc.ca/siplab

Burkhart, H. E. and Tomé{Tome}, M. (2012) Modeling Forest Trees and Stands. Springer.